# Elevated Plasma Progastrin-Releasing Peptide Levels Associated With the Diagnosis of Pulmonary Carcinoid Tumors: A Report of Two Cases

## TL;DR

High levels of a specific peptide in the blood may help diagnose a rare type of lung cancer called pulmonary carcinoid.

## Contribution

The study reports that elevated plasma ProGRP levels are associated with pulmonary carcinoid tumors and decrease after surgery.

## Key findings

- Plasma ProGRP levels were elevated in both patients diagnosed with pulmonary carcinoid tumors.
- ProGRP levels decreased after surgical resection in both cases.
- Elevated ProGRP may serve as a useful diagnostic marker for pulmonary carcinoids.

## Abstract

Pulmonary carcinoids are the type of thoracic malignant tumors classified as neuroendocrine tumors. Case 1 involved a 59-year-old woman with a nodular shadow in the left upper pulmonary field observed on chest radiography. Chest computed tomography (CT) scan revealed a nodule in the left upper lobe and a soft tissue tumor near the left third rib. Given her elevated plasma progastrin-releasing peptide (ProGRP) level, a CT-guided biopsy was performed, confirming a diagnosis of pulmonary carcinoid with solitary bone metastasis. She subsequently underwent partial resection of the left upper lobe and the rib tumor. Case 2 involved a 67-year-old woman referred to our hospital after a chest CT scan revealed a nodule in the left lingular region. Her plasma ProGRP level was elevated, and a CT-guided biopsy confirmed a diagnosis of pulmonary carcinoid. As no lymph node metastases were detected, she underwent segmental resection of the left upper lobe. In both cases, plasma ProGRP levels decreased following surgical resection. These findings suggest that plasma ProGRP levels may serve as a useful diagnostic marker for pulmonary carcinoids.